Plano, Texas, has some pretty ho-hum claims to fame: It’s home to junk-food headquarters Frito-Lay and the Dr. Pepper Snapple Group, for starters, as well as to retail giant J.C. Penney. But it’s also America’s safest city by our determination, and that’s nothing to yawn at.

Plano, a city of 278,000 that’s just outside Dallas, boasts the lowest violent crime rate of the cities we looked at and the sixth-lowest traffic fatality rate, putting it tops on our list for the second year in a row. The Las Vegas suburb of Henderson, Nev., and Honolulu come in second and third, respectively.

So what makes these metropolises oases of relative tranquility? Wealth is one key factor.

“One of the underlying things, in terms of a city’s safety, would be a very strong tax base, as there are a number of services that are reliant on it,” notes Scott B. Clark, president of the New York-based Risk and Insurance Management Society. “That includes an effective, well-staffed police department, fire department and school system.”

The median household income in Plano is $79,234, according to the U.S. Census Bureau, nearly 60% above the national average, and 8.1% of residents are below the poverty line, compared to a national rate of 15.1%. The city is also home to a number of Fortune 500 companies.

“Plano is a very clean, affluent suburb with no inner city per se,” says John Worrall, head of the criminology program at the University of Texas at Dallas. “Plus it has one of the few police departments in the U.S. that require four-year degrees. I don’t know that there is research to back up its making things safer, but it makes Plano unique.”

Plano boasts strong citizen involvement in public safety: the U.S. Department of Justice honored the city last year with a National Award for Excellence in Neighborhood Watch. Plano Police Chief Greg Rushin says his department works with 194 volunteers who help with tasks from patrolling neighborhoods to manning observation towers in public places and monitoring security camera feeds.

Henderson, Nev., takes the No. 2 spot despite its location within the Metropolitan Statistical Area of Las Vegas-Paradise, which ranked ninth this year on Forbes’ list of America’s Most Dangerous Cities. That may be because Henderson has a relatively high median income of $61,861, a low poverty rate (7%) and higher median home prices than Las Vegas, points out Tamara Madensen, a criminology professor at the University of Nevada in Las Vegas. Also of help, she adds, is that “casinos in Henderson cater mainly to local residents, which reduces traffic and the number of tourists moving about in the city.”

That’s an important point compared to Vegas: Since crime rates are calculated based on Census populations, violent crimes involving tourists inflate the numbers. “The number of people who visit the Strip and downtown Las Vegas each year,” over 35 million, “make it difficult to estimate the real ‘risk’ of crime for individuals living in Las Vegas. Tourist numbers are rarely factored into risk analyses,” Madensen says.

Behind the Numbers

To find America's 10 safest cities, we looked at metropolises with populations above 250,000. We ranked them by violent crime rates—the number of violent crimes (murder, forcible rape, robbery and aggravated assault) per 100,000 residents in 2010, as reported by the Federal Bureau of Investigation. Because the FBI only compiles data from municipalities that submit complete reports, we were only able to look at 72 cities; Chicago was not included in our ranking.

We also ranked each city on the traffic-fatality rate per 100,000 residents based on 2009 data, the most recent available, from the National Highway Traffic Safety Administration. We then averaged the ranking for each city to arrive at final scores. In the event of ties, the city with the lower crime rate got the higher ranking.

In third place on our list is Honolulu, which ranks fourth lowest for violent crime and seventh lowest for traffic fatalities. The city is relatively well off, with a median household income of $54,828, above the national average of $50,046, and a below average poverty rate of 10.5%. Hawaii has some of the strictest gun control laws in the nation, and that famous relaxed aloha spirit may play a role in keeping accident and violence rates low. “Honolulu is kind of like a big small town where everyone seems connected,” says Dave Kahaulelio, president of the Honolulu chapter of the Risk and Insurance Management Society.

Kahaulelio also notes a key factor behind Honolulu’s low traffic-fatality rate—4.27 per 100,000— is gridlock. “Our roads are often congested because we have two main arteries,” he says.

Russ Rader, vice president of communications for the Insurance Institute for Highway Safety, concurs that congestion is a good thing when it comes to traffic safety. “If traffic is often gridlocked, no one can drive fast enough to kill themselves or others,” he says. “Cities, by their nature, tend to have low fatality rates because speeds are low and traffic is dense, while rural roads tend to be more dangerous.”

That certainly rings true in the biggest city—and perhaps biggest surprise—on our list: New York City at No. 10. Major arteries are frequently backed up there, which may well explain why Gotham ranked No. 3 for lowest traffic-fatality rates, with just 3.17 per 100,000. Good public transportation and a relatively low car ownership rate also help.

But how to explain New York City’s relatively low violent-crime rate of 582 per 100,000, 27th-lowest among U.S. cities over 250,000 in population? Criminal justice professor Mike Maxfield, of John Jay College in New York City, points out that it has most of the resources that are key to urban safety: “wealth, effective policing and other guardianship, public spaces that are heavily used by a broad cross-section of people, institutions that attract people—parks, museums, shopping, entertainment—and effective governance, generally.”

But the Big Apple is still a mixed bag. “It’s also incredibly diverse with a great deal of inequality. That means that though New York is statistically safe as a city, safety, like wealth, is unevenly distributed,” Maxfield adds. “All of New York is better governed and better policed than 20 years ago and violence is lower everywhere. But it’s much lower in some places than in others.”

An earlier version of this article included a photo that was incorrectly identified as Aurora, Colo. The image was of Stapleton, Colo. and not Aurora, Colo.

Sprouted in NJ and planted firmly in NYC, my sense of wanderlust has taken me to all but three states in the union (sorry, MT, ND, and MN!) and a slew of countries—from India and Turkey to Cuba and Mexico (my favorite). I love a fab hotel. A former editor at Time Out New Yo...